The use of heavy agricultural equipment and tractors and the continuous moldboard plowing of agricultural soil at the same depth creates plow sole or hardpan immediately below the normal plowing depth. The hardpan forms a barrier which hinders the penetration and circulation of water into the ground and prevents tap roots of plants to grow downwardly into the soil where they can utilize the subsoil nutrients and moisture. When the surface of the ground is wet, excessive moisture becomes run-off water and is lost because hardpan prevents the water from percolating into the subsoil.
Deep tillage implements have been developed to penetrate and break up the hardpan so that the soil is open, allowing moisture and roots to go down into the subsoil. The implements have a plurality of downwardly directed tools mounted on a tool bar. The tool bar is connected to a hitch of a tractor. Examples of tool bar deep tillage implements are shown in U.S. Pat. Nos. 3,352,598; 3,461,971 and 3,503,456. These subsoil working implements have stationary ground working tools and require large horsepower tractors to pull the tools through the soil. Cultivators having earthworking tools connected to a sonic energy unit have been used for breaking, turning and conditioning the soil. An example of the sonic earth cultivator machine is shown by Bodine in U.S. Pat. No. 3,231,025. Vibrator units mounted on tool bars have been used to vibrate ripper and chisel tools attached to the tool bars.